There has been proposed an abnormality determining device that determines abnormal heating of a sensing subject based on a sensor signal outputted from a state detection sensor, which detects a state of the sensing subject (see, for example, the patent literature 1). That is, the abnormality determining device includes the state detection sensor that has a temperature sensor, which senses a temperature of a surface of an upper portion of the sensing subject, and a temperature sensor, which senses a temperature of a surface of a lower portion of the sensing subject. The sensing subject is a subject that generates convection through the heat generation. The abnormality determining device determines presence of the abnormal heating of the sensing subject based on a temperature difference between the temperature of the surface of the upper portion and the temperature of the surface of the lower portion of the sensing subject.
However, in this type of state detection sensor, the temperature sensors are exposed to the surrounding atmosphere, so that this type of state detection sensor is susceptible to the influence of the temperature change caused by the surrounding atmosphere. Therefore, in the above-described state detection sensor, there is a disadvantage of that the temperature (state) of the sensing subject may not be accurately sensed depending on the state of the surrounding atmosphere. In the abnormality determining device, which uses this type of state detection sensor, since the temperature (state) of the sensing subject cannot be accurately sensed with the state detection sensor, the abnormality determination of the sensing subject may not be accurately executed in some cases.